@article{IM2_1970_4_4_a9,
     author = {Yu. F. Korobeinik},
     title = {Differential equations of infinite order and infinite systems of},
     journal = {Izvestiya. Mathematics},
     pages = {891--930},
     year = {1970},
     volume = {4},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1970_4_4_a9/}
}